1. Field of the Invention
The present invention generally relates to band allocation methods, communication control units and communication apparatuses, and more particularly to a band allocation method and a communication control unit capable of reallocating bands with respect to a communication apparatus that is connected using a bus system, such as a high-speed serial bus in conformance with the IEEE1394 communication standard, which can be connected to an information processing apparatus such as a personal computer, a peripheral equipment thereof and an Audio Visual (AV) equipment, and to a communication apparatus which employs such a band allocation method.
2. Description of the Related Art
The band usable in an isochronous communication in conformance with the IEEE1394 communication standard is acquired by each node by requesting the band to an Isochronous Resource Manager (IRM). Each node can acquire the transfer band in the order in which the requests are made.
An information transfer system, a network apparatus, a data transmission control method and a communication resource managing method in conformance with the IEEE1394 communication standard have been proposed in Japanese Laid-Open Patent Applications No. 2004-241885, No. 2003-78527, No. 2005-12260 and No. 2003-204339.
In the case of the isochronous communication in conformance with the IEEE1394 communication standard, the band acquired by each node cannot be changed unless a next bus reset occurs. For this reason, the node which could not acquire the transfer band that was originally required must wait for the next bus reset before acquiring the transfer band. As a result, there was a problem in that the communication efficiency deteriorates.
In addition, in order to prevent the nodes that are connected to the same bus system from becoming unable to acquire the respective transfer bands, the system configuration is generally designed in advance so that the number of nodes that are connected to the same bus system and the number of transfer bands used are limited. For this reason, there was a problem in that it is difficult to improve the extendibility of the nodes to be connected to the same bus system, such as adding the nodes having various kinds of performances.